Fraley syndrome is a condition where the superior infundibulum of the upper calyx of the kidney is obstructed by the crossing renal (upper or middle section) artery branch, causing distension and dilatation of the calyx and presenting clinically as haematuria and nephralgia (ipsilateral flank pain). Furthermore, when the renal artery obstructs the proximal collecting system, filling defects can occur anywhere in the calyces, pelvis, or ureter. The condition was first described in the New England Journal of Medicine by urologist Elwin E. Fraley in December 1966. While this is a rare disorder, most cases are asymptomatic. When complications do arise, it can be treated surgically after testing is done to identify the renal vasculature that is impacting renal output. Another possible cause for similar hydronephrosis is megacalicosis, for which surgery is considered inappropriate. Signs and symptoms The signs and symptoms of this disorder can vary from asymptomatic microhematuria to severe, recurrent flank pain associated with kidney stone formation and infections. Patients may also present with a fever, nausea, vomiting, dysuria and polyuria. If untreated, the chronic infections can progress causing renal damage. In rare circumstances, it can also cause sepsis and overt kidney failure, though this outcome is very unlikely. Cause The symptoms are caused when the individual has an anatomically low lying kidney. This is known as ptosis of the kidney. This occurs normally on the right side, but bilateral involvement is possible. The reason that the right side is more commonly affected is because the vasculature on this side tends to be longer due to the positioning of the aorta, which lies slightly left of the midline. The renal vessels may then drape over a portion of the superior infundibulum causing compression, and ultimately partial obstruction to the superior calyces. When the obstruction occurs, distension of the calyx, which is known as hydronephrosis, leads to the clinical presentation of the disorder. Pathophysiology When a blood vessel, usually the renal artery, crosses over the superior infundibulum of the kidney (one or both), fluid begins to build up, causing the calyx to become distended. This stretching allows the backed up fluid to be more evenly distributed, which can slow the amount of damage done on the kidney. Within this area, the ability to remove waste and maintain mineral and fluid balance become impaired. This leads to an increased risk of infection and stone formation, often causing flank pain. Furthermore, infections